AIM: This study evaluated, through a systematic review of the literature, the outcome of single-implant restorations in the aesthetic zone with natural adjacent teeth, thereby addressing immediate, early and conventional implant approaches. MATERIAL AND METHODS: MEDLINE (1950-2008), EMBASE (1966-2008), and CENTRAL (1800-2008) were searched to identify eligible studies. Two reviewers independently assessed the methodological quality using specific study-design-related assessment forms. RESULTS: Out of 86 primarily selected articles, 19 studies fulfilled the inclusion criteria. A meta-analysis showed an overall survival rate of 95.5% [95% confidence interval: (93.0-97.1)] after 1 year. A stratified meta-analysis revealed no differences in survival between immediate, early and conventional implant strategies. Little marginal peri-implant bone resorption was found together with low incidence of biological and technical complications. No significant differences in outcome measures were reported in clinical trials comparing immediate, early or conventional implant strategies. CONCLUSION: The included literature suggested that promising short-term results could be achieved for immediate, early and conventional single-implants in the aesthetic zone. However, important parameters as aesthetic outcome, soft-tissue aspects, and patient satisfaction were clearly underexposed. The question whether immediate and early single-implant therapies would result in better treatment outcomes remained inconclusive due to lack of well-designed controlled clinical studies. [References: 64]

Outcomes for single implant crowns in the aesthetic zone.

Gerard Byrne BDSc MSD
.

Overview

Systematic Review Conclusion

Pooled data show similar outcomes for implant survival and bone loss, while other outcomes are inconclusive with different placement and loading protocols for single-tooth implants in the esthetic zone.

Critical Summary Assessment

There is insufficient evidence to draw definitive conclusions about the effect of implant placement protocols on aesthetic outcomes.

Evidence Quality Rating

Limited Evidence

Structured Abstract

Clinical Questions:

Are there any differences in outcomes (survival, bone levels, soft tissues, esthetics, patient satisfaction, complications) between immediate, early and conventional placement/ loading protocols for single-tooth implants in the esthetic zone?

Review Methods:

The authors searched three electronic databases through 2007 for articles published in English, German, French, Spanish, Italian and Dutch. They also completed a hand search of relevant review references. Their search included randomized controlled trials, clinical trials, cohort studies and case series with a minimum of five subjects. Studies had to have a minimum follow-up period of one year after prosthesis placement. Study quality was assessed using Dutch Cochrane Collaboration forms. Two observers independently assessed case series. Two authors independently extracted data and isolated studies that evaluated subjects with bounded single edentulous spaces in the incisor-to-second premolar region, and involved immediate, early and conventional placement and loading protocols for single tooth implants. The following outcomes were assessed; implant survival, marginal bone level, esthetics, peri-implant tissue health, patient satisfaction, and complications. Two independent reviewers screened full-text articles.

Main Results:

Nineteen studies met the inclusion criteria, totaling 499 patients and 509 single-tooth implants; only 38 implants were placed in the mandible. There were five RCTs, two clinical trials, and 12 case series; RCTs and CTs compared placement and loading protocols, while remainder studied only one approach. A total of 14 implants did not survive and all were lost within six months of placement. Statistical analysis was conducted for implant survival using data from all studies, however fewer studies could be analysed (combined ) to evaluate bone loss. Analysis of 15 studies showed an implant survival rate after one year of 95.5 percent (95 percent [CI], 93.0 to 97.1). A statistical analysis for 5 studies on bone loss revealed a mean bone loss of 0.2 mm (95 percent [CI], 0.034 to 0.36) for the year after definitive crown placement. Aesthetic outcome were reported in only three studies and patient satisfaction in only four studies. Measures of peri-implant structures trended toward gingival recession, although data were unsuitable for meta-analysis. Although the authors recorded complications in some studies, they did not analyze the information.

Conclusion:

Pooled data suggest similar short-term outcomes in terms of implant survival, marginal bone loss and incidence of complications for single tooth implants. No conclusions can be drawn about esthetics, patient satisfaction and soft tissue aspects because studies either did not report these outcomes, or were inadequately designed.

Source of Funding:

University of Groningen, Netherlands.

Commentary

Importance and Context:

Traditional implant strategies continue to evolve. One such approach emphasizes immediate/early placement and loading, with the goal of minimizing crestal bone loss while improving soft tissue healing around the prosthesis. The practitioner would benefit from learning about the treatment limitations of different clinical scenarios, as well as how to achieve predictable, optimal outcomes.

Strengths and Weaknesses of the Systematic Review:

The authors used accepted methods to identify and select appropriate studies. Their study selection process was rigorous. Because the studies varied greatly in methodology, the meta-analyses may be inappropriate for the available data. Also, these analyses pools survival data from all studies. The direct comparisons of treatment modalities reported in the RCTs and clinical trials. were not subnjected to a separate meta-analysis. The authors might have offered that more limited analysis of direct comparisons in addition to their indirect comparison of pooled data from studies without random treatment allocation. The authors presented the outcomes as a descriptive review, which is appropriate given the heterogeneity of the studies. Limited data precluded analyses of esthetic, patient satisfaction and peri-implant structures. The authors should have considered collating /analyzing complications related to implant failures, soft tissue problems or mechanical problems.

Strengths and Weaknesses of the Evidence:

In general, the studies are of too short duration, too heterogeneous with small samples. Also, the risk of bias prevented definitive conclusions from being drawn. The authors did not state if any of the included RCTs were blinded. Four RCTs (since one RCT, reported twice for the same patient group, but evaluated different outcomes) were supplemented by lower-level evidence studies. Implant survival was reported in all selected studies, while reporting of other outcomes was variable or unreported. Although useful, the data on aesthetics, patient satisfaction, and various complications were from uncontrolled studies. The authors did not disclose information about commercial interests, which may impact immediate placement protocols.

Implications for Dental Practice:

For immediate, early and conventional implant placement and loading protocols, pooled data showed an implant survival rate of 95.5%; there was no direct comparison between protocols. Evidence is inconclusive about the effect of placement protocol on esthetic outcomes, patient satisfaction, soft tissue response and complications (biological and mechanical).